消息信号是[-3,3]均匀分布的随机整数，产生的时间间隔为1/10s，用AM方法调制载波　　　　　 ，求息信号和已调信号的频谱。(The message signal is [-3,3] uniformly distributed random integer, the time interval is 1/10s, and the carrier is modulated by the AM method, and the spectrum of the message signal and the modulated signal is searched.)